R33 Gtst rear end knock

[admS15]

Recently car has developed a rear end knock. RHS. Noise is audible when taking off, slowing down and then accelerating again slowly, around corners accelerating slowly noise is also present. Sounds like something knocking against chassis, knock knock knock sound as suspension is loading/unloading. Noise is consistently there.
 
I have checked the obvious things, loose exhaust, rear bar, boot, anything inside boot, play in bushes. All look ok. There is a fair amount of diff backlash but no more than last time i checked when noise wasn't occuring. I have run the car on stands through the gears and no noises unloaded. There is no play when trying to wiggle the wheels at 9 and 3 o'clock or 6 and 12. Subframe has lock collars installed, bushes have seen better days but subframe seems secure.
 
I was suspecting rear coilovers or top hats. I removed them and inspected, all look and felt good, i greased the upper bearings and put back in on opposite sides to see if noise changed sides but its the same, rhs knock. This rules coilovers out.
 
Is it possible it could be the cv's? Im running out of things to look at and at my whits end with it. Probably going to take it past my trusted local mechanics for a look.
 
Rear end is also fitted with hicas lock bar, whiteline upper camber arms, traction arms and sway bar. Sway bar looked a bit close to subframe, so i removed it and went for a drive to see if the noise went away, no go there either.
 
Car drives and feels fine otherwise.
 
Anyone got any ideas what i can check before going to mechanics?

[GTSBoy]

CV, diff CW&P or internal gears, tailshaft centre bearing.  Any and all of these things.

[admS15]

CV, diff CW&P or internal gears, tailshaft centre bearing.  Any and all of these things.

Thanks for the response, i did already inspect the tail shaft centre bearing which was ok. When i get time, I'll have a better look at the rh driveshaft, from memory i do remember that one in the past having some unusual in/out play compared to the other side. I may remove it if i need to for a better look. I'll let you know how i go.

[Ben C34]

Does the noise occur when doing skids?

Vids for research purposes please.

[admS15]

Does the noise occur when doing skids?
Vids for research purposes please.

How do you think the noise developed in the first place.. Watch ACA for upcoming skid vid feature[emoji6]

[Dose Pipe Sutututu]

Still OEM subframe bushes? Even with subframe lock collars they will moved a tiny bit and will clunk.

I had that issue and went all jihadi-ish on the subframe bushes and replaced them.

Note to anyone trying to do it, just drive it to a shop. Not worth DIYing.

[admS15]

Yep still oem bushes. It is the last thing i hope it is. Cbf removing the subframe but if i have to, i'll strip it down and take it to a shop to press out/in.

 

Edit, i doubt it is the subframe because there is stuff all load occuring when the knock happens and i couldn't budge it with a pry bar but never say never heh.

 

[admS15]

Had a quick look over everything again today and didn't find anything. I ended up going to the local mechanics.

 

We put the car on the hoist and he checked/pryed everything and couldn't find anything obvious either. He agreed that although the diff backlash wasn't great, it wasn't the culprit. He was saying i may just have to keep on driving until it gets worse and shows itself.

 

At this point he hadn't driven the car yet, i had just demonstrated the noise in his driveway. I encouraged him to take it for a quick drive around the block to hear it for himself while driving. When he returned he said the noise isn't anything mechanical and sounds like something knocking around inside a panel, which was my initial thought also.

 

Now that i think about it, this only started happening after a recent rear end respray at a panel shop. Im thinking they've left something inside the rear right quarter. Either a tool, can/bottle of red bull or something. I had thought of this earlier and have looked everywhere except below the rear quarter windows, reason being I've got to remove the roll cage to get the trims off to get in there. Fuark, well i know what my next move is now and beats removing diffs and subframes. Should only take around half an hour to remove.

 

The saga continues, I'll update when and if i come up with anything.

 

 

[hardsteppa]

so adm, I had a similar issue recently as per posts in r200 diff rebuild thread.  After rebuilding rear cv's, diffcentre and buying a replacement tailshaft, the noise disappeared after I had the front tyres rotated side to side and rebalanced. I could have sworn the knocking was from the rear somewhere, seriously it seemed so tailshaft/diff located,  but after it conclusively disappeared post front wheel refit I can only assume it was a weight fallen off on the front wheels. Was extremely pronounced between 25-40 k's ph.

[admS15]

Thanks for the response@hardsteppa i had another look today, found nothing but an empty plastic money bag inside the 1/4. I also removed the removable panel at the rear firewall. Noise is now heard clearer so definitely points to back end. I was able to get the noise happening while stationary and i was in the back of the car rocking around. Im going to check out the fuel filler neck and inside the fuel tank for something loose.

The noise is a weird one, its only heard in changes of motion briefly, like something is swinging around and hitting something when it gets enough momentum.

I'll check the above and if its not that, I'm willing to try anything. Ive got a spare set of wheels i can throw on to rule out any wheel/tyre mounting issue. Whatever this ends up being, ive got a feeling its going to be something silly.

[GTSBoy]

Make sure the jack is snug in its spot.  Same with the toolbag.

[admS15]

Make sure the jack is snug in its spot.  Same with the toolbag.

All of that has been removed, including spare tyre, all boot trims,rear seats, trims, inspection hatch, parcel shelf. Even drove it without rear bumper bar and sway bar. Car is looking pretty bare atm.

[Ty1]

Hey man what brand are your coilovers? i had a very similar knocking noise to you but mine was in the front end. I literally felt like burning the car to the ground...it was that frustrating lol for me anyway it turned out to be a shot coilover which a certain suspension workshop completely missed. By looking at the coilover there were no visible signs of damage or any leaks but internally the piston had failed so i managed to replace the cartridge with a brand new one (bc/br coilover)

[admS15]

Hey@Ty1 coilovers are tein, i have already removed and swapped them from left to right with no change. I have a set of stock shocks and if i can't evetually find the noise i can always throw them in to 100% rule out coilovers.

I had a look in the fuel tank and found the float level tube loose and it was knocking around when wiggled. I was pretty convinced this was the source of the noise, i secured the float properly and went for a drive but noise still persists. Fuark! I'm still on the hunt.

[Ty1]

That is very strange then and would eliminate the coilovers. Are you certain what side of the car that the noise is coming from?

[admS15]

Im 90% sure its rear right but you know sometimes strange things happen and these noises can travel from elsewhere. Im trying to keep an open mind.

One good thing has happened so far, i found the source of an unrelated front end knock which was a couple loose bolts on a castor arm.

My next move is going to be to get a friend to drive while i get in the back/boot and listen to try and track it like that.

[admS15]

Bit of an update, swapped in the standard rear shocks yesterday, no change other than smooth boating around corners and bulk traction on launch.

Replaced the tein back in today and also replaced rear brake pads while i was at it. Went for a drive to bed in pads, no change. I stopped at 1 stage and popped the boot and my eye caught the aftermarket boot release solenoid, i just remembered the cable had popped off this a couple of times over the last month or two so i had a closer look. The internals seem to be loose as a goose and knocking around. I tightly secured the cable coming out of it against the frame of the boot with a zip tie and went for a drive, BOOM problem solved. FML, the time spent stuffing around on this could have been used to do useful stuff but just glad it is now solved and wasn't anything major. Ill try upload a video clip.

[admS15]

[GTSBoy]

Genuine pain in the arse.

[V28VX37]

Glad there's a happy ending!

Also, LOL